<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        * {
            margin: 0;
            padding: 0;
        }
        
        header,
        nav,
        section,
        footer {
            border: 1px solid black;
        }
        
        .header {
            height: 80px;
        }
        
        nav {
            height: 40px;
        }
        
        section {
            height: 1000px;
        }
        
        aside {
            float: left;
            height: 1000px;
            border: 1px solid black;
            width: 28%;
        }
        
        article {
            float: right;
            height: 1000px;
            width: 70%;
            border: 1px solid black;
        }
        
        footer {
            height: 50px;
        }
    </style>
</head>

<body>
    <header>头部</header>
    <nav>导航</nav>
    <section>
        <aside>侧边栏</aside>
        <article>内容</article>
    </section>
    <footer>底部</footer>
</body>

</html>